Wheat disease warning from summer rain

The West Australian
DAFWA’s Ciara Beard checks for powdery mildew.
Camera IconDAFWA’s Ciara Beard checks for powdery mildew. Credit: DAFWA

Wheat growers have been advised to review the latest disease rating of their chosen variety, with a heightened disease risk this season because of widespread summer rainfall.

Department of Agriculture and Food research officer Christine Zaicou-Kunesch said the variety disease rating would be crucial this year to develop a risk mitigation plan for cropping programs. “Rainfall has resulted in the potential for a green bridge of summer weeds and self-sown volunteer plants, which could harbour disease,” she said.

“As a result, leaf diseases, particularly powdery mildew and leaf rust, could be carried over from last year and be an issue this season.”

Mace is the most widely sown variety, with about 66 per cent sown to the variety in 2016, according to CBH Group data.

“Mace is moderately susceptible to leaf rust and moderately resistant to stem rust, while it is moderately susceptible to susceptible to powdery mildew,” Ms Zaicou-Kunesch said.

“The variety’s likely successor, Scepter, offers better rust protection, being moderately resistant to stem, stripe and leaf rust, while it has a provisional susceptible to very susceptible rating to powdery mildew.

“Given both Scepter and Mace’s susceptibility to powdery mildew, it is important for growers to monitor crops carefully and take appropriate action.”

Ms Zaicou-Kunesch said leaf rust resistance ratings have also been altered for some varieties, after the discovery of new pathotypes in the past five years.

Alongside the susceptibility of the wheat variety, disease severity is also influenced by the amount of inoculum carried over from the previous season, seasonal conditions and the virulence of the pathotype.

The disease ratings are available on agric.wa.gov.au, with a new Wheat Variety Factsheetcoming soon.

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